The verb wrapped the caller's text in BEGIN READ ONLY ... ROLLBACK as the superuser, so
'COMMIT; ...' left the transaction and, proven on a throwaway server, COPY TO PROGRAM ran a
shell command on the database host. The statement now runs as mesh_store_reader:
pg_read_all_data, no other grant, read-only transactions by role and session, its password
an own-secret the mesh mints. Without that password the call is refused. -q drops the
command tags that came back as rows keyed by BEGIN.